Sound propagating apparatus



March 26, 1946. J HAMMOND, JR 2,397,107

SOUND PROPAGATING APPARATUS Filed April 11, 1944 AMPLIFIER INVENTOR JOH N HAYS HAMMOND, \JR.

I 1 ORNEY Patented Mar. 26, 1946 STTE PATENT OFFHCE Claims.

This invention relates to sound producing apparatus and more particularly to apparatus for picking up and reproducing the sound of a vessels propeller.

In particular the invention provides means for picking up the sound of a vessels propellers, amplifying the same and reproducing the amplified sound at a distance from the vessel.

The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of is organization ma be better understood by referring to the following description taken in connection with the accompanying drawing forming a part thereof, in which Fig. 1 illustrates diagrammatically the pickup, amplifying and sound propagating apparatus embodying the present invention; and

Fig. 2 is a cross section of the sound reproducing apparatus taken on line 2-2 of Fig. 1.

Like reference character denote like parts in the several figures of the drawing.

In the following description parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Referring to the accompanying drawing and more particularly to Fig. l a vessel H is provided with the usual propeller l2 and rudder l3. Mounted on the hull of the vessel H and adjacent to the propeller I 2 is a microphone M which is connected by conductors I 5 to the input circuit of an amplifier it, which may be of any well known and standard construction. The output circuit of the amplifier I5 is connected by a cable H to a pair of loud speakers l8, mounted in a fish I9 which is towed a considerable distance behind the vessel II by means of the cable IT. The speakers 88 are positioned to impress compressional waves onto the surrounding water. The speakers are preferably mounted in the fish l9 and are connected to drive one or more external diaphragms 20 which are in contact with the water but are waterproof and prevent the sea water from afiecting the speaker itself.

The fish I9 is shown as provided with diving planes 2| and tail fins 22 and may be similar in construction to the fish shown in U. S. Patent No. 1,625,245, issued April 19, 1927, to H. G. Dorsey.

Operation In the operation of this invention the microphone 14 picks up the noise produced in the water by the propeller I2 and also any noises emanating from the hull of the vessel II. The energy from the microphone I4 is fed over the conductors l5 to the input circuit of the amplifier it. This energy is then amplified by the amplifier l6 and the output energy is fed thru the cable I I to the loud speakers l8 where it is broadcast thru the water as compressional waves emanating from the fish I9. The amplifier is preferably capable of producing sufiicient energy to produce compressional waves of an intensity greater than those produced by the vessel 1 I,

In this way a sound producing apparatus is provided at a considerable distance behind the vessel, so that any sound detecting devices, either on enemy submarines or on sound controlled torpedoes will mistake the sound produced by the loud speakers l8 for the sound produced by the vessels propeller l2 and will cause the torpedo to be directed at the fish l9 rather than at the vessel I I.

Although only one of the various forms in which this invention may be embodied has been shown herein, it is to be understood that the invention may be embodied in various forms without departing from the spirit of the invention as defined by the appended claims.

What is claimed is:

1. Apparatus for protecting vessels, comprising a member to be towed a substantial distance behind said vessel, a compressional wave generator on said member responsive to received energy and having means to produce and propagate compressional waves through the water, means picking up the sound produced by the towing vessel, and means supplying the picked-up sound energy to actuate said generator for reproducing the same as compressional waves of increased intensity in the water.

2. Apparatus for protecting vessels, comprising a member to be towed a substantial distance behind said vessel, a compressional wave generator on said member responsive to received energy and having means to produce and propagate compressional waves through the water, means on the towing vessel to pick up the sound produced thereby, and a transmission channel transmitting the picked-up energy to actuate said generator for reproducing the same as compressional waves of increased intensity in the water.

hind said vessel, means picking up the sound produced by said vessel and converting the same to electrical energy, means transmitting said electrical energy to said member, means on said member converting said electrical energy to mechanical energy and means responsive to said mechanical energy to propagate compressional waves or increased intensity through the water from said member.

4. Apparatus for protecting vessels, comprising a member to be towed a substantial distance behind said vessel, a compressional wave generator on said member responsive to received energy and having means to produce and propagate compressional waves through the water, a microphone on said vessel positioned to pick up the sound thereof, and a circuit connecting said microphone to actuate said generator for reproducing the sound as compressional waves oi increased intensity in the water.

5. Apparatus for protecting vessels, comprising a member to be towed a substantial distance behind said vessel, a compressional wave generator on said member responsive to received energy and having means to produce and propagate compressional waves through the water, a microphone on said vessel positioned to pick up the sound thereof, an amplifier fed by said microphone and a circuit connecting the output of said amplifier to actuate said generator for reproducing the sound as compressional waves of increased intensity in the water. 1

JOHN HAYS HAMIMOND, JR. 

